Modern society is characterized, in part, by very large edifices, buildings or structures. In general, a person who is newly introduced to large building cannot use his knowledge of other buildings to navigate within the particular building in which he finds himself. While merely inconvenient for visitors, this difficulty in navigation can be of great importance to emergency personnel. In the event of an emergency, rescue personnel must expediently navigate the building without prior knowledge of that building, and under adverse conditions such as flame, heat, smoke, noise, and the like. The adverse condition may even include hostile terrorist action directed against those within the building.
Maps of the building, whether portable or affixed to walls of the building at particular locations, can be useful. However, most people do not carry maps of the building in which they happen to be present. Those maps which are affixed to a wall may or may not be up-to-date, but in any case are not likely to be located where they are needed, especially in an emergency.
Another possible way to identify one's location within a building is to use a cell-phone to contact someone familiar with the building, explain as best one can where one is, then obtain directions to the desired location. However, cell-phone reception may be unreliable, especially in adverse circumstances. Also, some high-security buildings are constructed so as to prevent cell-phone signal propagation. Even if cell-phone communications are available, the necessity of identifying one's location to the person familiar with the building may be time-consuming and prone to error. Lastly, this technique may not be usable unless one is able to contact a person familiar with the building, who is also willing and able to provide directions. If the person requiring directions within the building does not happen to know the cell-phone number of such a person, even good cell-phone communications are unavailing.
Portable Global Positioning System (GPS) receivers could, in principle, provide the latitude and longitude of a person's location in a building, if the structure of the building were such as to allow the GPS signals to reach the GPS receiver. However, most large buildings are made with a steel framework, which together with the large amount of lossy and reflective dielectric material of the structure tend to make GPS reception spotty or unreliable. Even if a GPS signal is available, the latitude, longitude and altitude information is not particularly useful in the confines of a building without proper correlation to a location on a map of the building. The civilian accuracy of un-aided GPS is not sufficient to properly place a user in a hallway instead of in a room off the hallway.
Improved arrangements are desired for personal and personnel location within buildings.